This invention relates to an occlusion device for the closure of a physical lumen. More specifically, this invention relates to an occlusion device for the left atrial appendage of the heart.
The heart is generally comprised of four chambers: the left and right atrium, and the left and right ventricle. Additionally, a small cavity called the left atrial appendage (LAA) is located off the left atrium between the mitral valve and the left pulmonary vein. Thus, the LAA opens into the left atrium of the heart. The LAA is shaped like a small thumb which terminates as it tapers away from the opening.
In a healthy heart, the LAA contracts as the heart contracts. In individuals diagnosed with atrial fibrillation (AF), however, the LAA may not contract with enough force to expel all of the blood from the LAA. In individuals diagnosed with AF, the electrical activity of the atrium becomes very rapid and disorganized. Thus, the heart beats quickly and may not get enough time in between beats to fill up with blood. As a result, only a small amount of blood is pumped out of the heart with each beat, and the cardiac output drops significantly. Therefore, stagnant blood may easily remain in the LAA. Because clotting occurs when blood is stagnant, clots or thrombi may form in the LAA. If a blood clot leaves the LAA and becomes lodged in an artery in the brain, a stroke results.
Approximately 15 percent of strokes occur in people diagnosed with AF. Approximately 2 million Americans have been diagnosed with AF. Studies indicate that more than 90 percent of non-rheumatic atrial fibrillation related strokes result from a blood clot that has formed in the left atrial appendage. Anti-clotting drugs may be used to prevent strokes in patients diagnosed with AF. However, many people cannot take such drugs because of potential side effects. Drug therapy may also cause bleeding and may be difficult to control because determining dosage is challenging. Recent studies indicate that elimination of the LAA, through occlusion or closure, may prevent thrombi from forming in the LAA and thus may reduce the incidence of stroke in patients diagnosed with AF. As such, occlusion or closure of the LAA may significantly reduce the incidence of stroke in patients with atrial fibrillation and without the complications of drug therapy.
The LAA may be sealed off during open heart surgery, which is a risky, painful, and expensive procedure. Surgery for closure of the LAA is major heart surgery, which requires the patient to undergo general anesthesia and opening of the chest cavity. The patient must spend several days in the hospital and thereafter may take several weeks to be able to return to normal levels of activity.
To avoid the risks and discomfort associated with open heart surgery, modem occlusion devices have been developed that are small, implantable devices capable of being delivered to the heart through a catheter. Rather than surgery, a catheter inserted into a major blood vessel allows an occlusion device to be deployed at the defect once the device has been moved through the catheter to the treatment site. This procedure is performed in a cardiac cathlab and avoids the risks and pain associated with open heart surgery. These devices have proven effective at sealing defects in the heart and could likewise be used to occlude the LAA without requiring open heart surgery.
Thus, there is a need in the art for a LAA occlusion device which can be implanted using a catheter to avoid heart surgery and which may provide an alternative to drug therapy.